The present invention relates to a charge method of a battery for an electric motor vehicle and a charge device of a battery for an electric motor vehicle.
In these days, electric motor vehicles which are driven by an electric motor receiving an electric power supplied from a battery have become noticeable. In these electric motor vehicles, it may be necessary that the battery is charged by an outside electric source when a residual charge quantity of the battery becomes small. However, the number of the electric motor vehicles spreading is still small, so there are not sufficiently many places where the outside electric source is located. Accordingly, there is a concern that the charging of the battery by the outside electric source could not be necessarily conducted properly when the residual charge quantity of the battery becomes small and the charging becomes necessary. Therefore, it should be necessary that the battery has been charged sufficiently during the vehicle's driving stop.
Meanwhile, there is a concern that the motor of the electric motor vehicle could not be started properly in a cold season unless the battery is warmed up, so that the vehicle's driving would not be started promptly. This is because of the battery's characteristics, in which the output voltage decreases depending on the decrease of the surrounding temperature of the battery, so that the sufficient electric power may not be supplied to the motor.
Japanese Patent Laid-Open Publication No. 7-111736 discloses the charge device of the battery, which may be one of countermeasures against the above-described concern, in which the battery charging has been so properly conducted during the vehicle's driving stop that the battery can be warmed up sufficiently (to a proper temperature) at the start of the vehicle's driving. That is, according to this charge device, the timer for setting a driving-start time of the vehicle is provided, and the time for starting the charge of the battery is calculated based on this set driving-start time so that the battery charging can be completed at the driving-start time of the vehicle. Thus, the battery charging is automatically started when the time has come to this calculated time for starting the charging of the battery after the vehicle's driving stop, and this battery charging is completed when the vehicle's driving is started again. Thereby, the battery has been warmed up sufficiently at the timing of the vehicle's driving start even in the cold season, thereby enabling the prompt vehicle's driving start.
However, the charging of the battery by the charge device of the above-described patent publication is started from a charge start time which is calculated based on the driving-start time of the vehicle. That is, no charging is conducted during a period from the vehicle's driving stop to this charge start time. Accordingly, in case the residual charge quantity of the battery is small when the vehicle's driving is stopped, if a driver wants to drive the vehicle before the charge start time, the motor may not operate. Or, even if the motor may operate, the residual charge quantity of the battery may not be sufficient, so that the vehicle may not be driven for a sufficiently long period.